"JUSTICE BLACKMUN takes us to task for our failure to join in a "great issues" debate as to whether the Constitution includes an "unenumerated" general right to privacy as recognized in cases such as Griswold v. Connecticut, 381 U. S. 479 (1965), and Roe. But Griswold v. Connecticut, unlike Roe, did not purport to adopt a whole framework, complete with detailed rules and distinctions, to govern the cases in which the asserted liberty interest would apply. As such, it was far different from the opinion, if not the holding, of Roe v. Wade, which sought to establish a constitutional framework for judging state regulation of abortion during the entire term of pregnancy. That framework sought to deal with areas of medical practice traditionally subject to state regulation, and it sought to balance once and for all by reference only to the calendar the claims of the State to protect the fetus as a form of human life against the claims of a woman to decide for herself whether or not to abort a fetus she was carrying. The experience of the Court in applying Roe v. Wade in later cases, see supra at 492 U. S. 518, n. 15, suggests to us that there is wisdom in not unnecessarily attempting to elaborate the abstract differences between a "fundamental right" to abortion, as the Court described it in Akron, 462 U.S. at 462 U. S. 420, n. 1, a "limited fundamental constitutional right," which JUSTICE BLACKMUN today treats Roe as having established, post at 492 U. S. 555, or a liberty interest protected by the Due Process Clause, which we believe it to be. The Missouri testing requirement here is reasonably designed to ensure that abortions are not performed where the fetus is viable -- an end which all concede is legitimate -- and that is sufficient to sustain its constitutionality."